Process for treating crucibles, &amp;c.



UNITED STATES PATENT oFFIoE.

I WILLIAM ROY MITCHELL, OF NEW YQRK, N. Y.

PROCESS FOR TREATING CRUGIBLES, 860.

Specification of Letters Patent.

Patented Aug. 4, 1908.

Application filed May 14, 1907. Serial No. 373,628.

for Treating Crucib es, &c.'; and I do hereby declare the following tobe a full, clear, and exact description of the invention, such as willenable others skilled in the art to which it appertains to make and usethe same.

My invention relates to a rocess for treating crucibles and other vesses to render them moisture-proof and therefore proof against scal ing andcracking when heated whereby the ife of each crucible or vessel, thatis, the number of heatings it will stand, is increased from fifty to onehundredper cent.

Heretofore it has been necessary to subject all crucibles, pots, etc.,to a slow heating process known as annealing in order .to drive out themoisture that gathers and becomes absorbed in the walls .thereof so thatthe high heating necessary to melt metals would not convert the moistureinto steam which, 6X. panding quickly, would crack or break the vesselsand render them worthless. Unless vessels are kept in warm ovens awayfrom dampness or moisture when not in use, this process of annealingmust be repeated each time they are used. I

The object of my present invention is to provide a crucible or othervessel which will e impervious to, moisture and which will, therefore,not have to bekept in warm ovens or annealed every time it is to beused. In fact, crucibles after being treated'with my process may beplaced in water and immediately afterward plunged into a very high heatwithout injury.v a 4 The process or treatment to which I sub- 'ect thecrucibles or vessels consists in first eating them slowly and graduallybringing them to a high tem erature. Then the vessels are filled or party filled with, copperas or ferrous sulfate and the high heat continueduntil the ferrous sulfateis absorbed by the walls of said vessels. Whenferrous sulfate is heated, it first becomes a semi-liquid mass or paste.During the heating. of this substance in a crucible, some of the Hastyor watery mass is absorbed by the Wa s of the vessel while the remaindersolidifies. That which is absorbed by the crucible closes up the poresinthe walls so that moisture cannot enter, thereby preventing crackingand scalping and greatly increasing the life of the crucible.This'process may be repeated as many times as may benecessary ordesirable, it being understood that the oftener it is repeated theharder and more durable will the vessels become. Said vessels are thentaken out of the fire and cooled, preferably by plunging them intowater, but I do not wish to limit myself to cooling them in that way.

the outside of the vessels by setting one inside of another with thesame success.

kinds and makes of crucibles no matter what their composition is,although those more gen erally used contain a mixture of graphite orclay. The process is also applicable to-any form, or shape of pots, bows, j are, dippers, ladles or even graphite tubes or sticks and stirrersor anything made of a substance that is liable to crack or seal onaccount of its coniiaiging moisture within itself when heat is .a re 1 pf desired, theferrous sulfate may be put in thecrucible while the latteris cold and both be heated together until the ferrous sulfate isabsorbed by' the walls of the crucible.

1. Aprocess of treating a vessel of the character described to render itmoisture proof, which consists in heating ferrous sulfate therein untilthe pores in the walls thereof are closed to moisture.

2. A process of treating a vessel of the character describedv to renderit moisture proof, which consists in first heating it and then treatingit with ferrous sulfate. 3. A process of treating a vessel of thecharacter described to render it moisture -proof, which consists infirst heating it, then treating it with ferrous sulfate and continuingthe heating until the pores of the walls thereof are closed to moisture.

41 A process of treating a vessel of the character described to renderit moisture proof, which consists in first heating it, then treating itwith ferrous sulfate and continuing the'heating until the pores of thewalls ther'eof'are closed to moisture and finallycooling said vessel.

5. A process of character described to render it moisture roof, which'crmsists in first heating it to a ugh temperature, then treating itwith ferrous sulfate amleoutinuing the heating at The ferrous sulfatebath may beapplied to- It should be understood that my process may beemployed in the treatment of all treating a vessel of the.

a high temperature until the pores of the proof, which consists inheating ferrous sulwalls thereof are closed to moisture. l fate thereinuntil said ferrous sulfate is re- 6. A process of treating a vessel ofthe i duced to a watery or pasty mass and enters character described torender it moisture i and closes the pores of the walls of said vessel 1:5 proof which consists in first heating it slowly against moisture.

and gradually to a high temperature, then 1 In testimony whereof,l allixmy signature, treating it with ferrous sulfate and continu- 1 inpresence of two witnesses. ing the heating until the pores of the wallsl/VILLIAM R01 MITCHELL. of the vessel are closed to moisture. vWitnesses: 10 7. A process of treating a Vessel of the HyN. BAILEY,character described, to render it moisturel E. E. ARCHER.

